Cycle Life and Throughput Warranty
Definition
Cycle life is the number of full charge and discharge cycles a battery can perform before its capacity falls to a defined end-of-life level. A throughput warranty or cycle limit caps how much energy may pass through the battery, often expressed as equivalent full cycles per year, while the manufacturer's capacity warranty stays in force. Operating beyond those limits can speed degradation and void warranty coverage, so extra cycles carry a cost as well as revenue.
Why it matters
Merchant battery revenue rises with cycling, but so do degradation and the risk of breaching warranty limits. A projection that assumes two cycles a day under a warranty that allows one, or that ignores the cost of each cycle, overstates value. Investors should compare the cycling assumed in projections with the warranty's throughput limit and with the augmentation budget.
Common misconceptions
- •A cycle-life figure is not a guarantee of years; how hard the battery is used decides how long the cycles last.
- •Warranty limits are operating constraints, not targets.
- •Shallow cycles still count toward throughput.
- •The label is only a starting point. Investor outcomes usually depend on the governing documents, cash-flow priority, valuation policy, disclosure quality, and manager discretion surrounding the term, not just the shorthand definition used in marketing materials.
Technical details
Warranty conditions to read
Annual or lifetime throughput or equivalent-full-cycle cap.
State of charge window and temperature range.
Maximum charge and discharge rate.
Capacity guarantee and end-of-life threshold.
Who measures throughput and how.
Worked figures
Marviken: 731 equivalent full cycles per year allowed, 90% market availability required, operator paid 9% of top-line revenue.
Nomad: about 365 cycles a year, about 6,205 over a 17-year estimated life, 70.8% end-of-life capacity.
How investors apply the term
Investors usually apply this term by tying the definition back to the controlling documents and then asking which cash flows, rights, restrictions, or valuation assumptions it changes. A useful review looks at the term alongside fees, leverage, liquidity, reporting frequency, and manager discretion rather than treating it as a standalone concept.
The practical diligence test is simple: identify who benefits if the assumption is wrong, who has control when conditions change, and what evidence the investor receives after closing. Terms that cannot be reconciled to documents, cash movements, and monitoring data should be treated as marketing shorthand until proven otherwise.
Frequently asked questions
- Does cycling a battery more often always increase returns?
- No. Each additional cycle earns a price spread but uses up cycle life and warranty allowance. The Marviken battery agreement, filed by Nuvve in March 2026, says the operator 'shall not exceed the maximum of 731 equivalent full cycles per calendar year,' calculated from net energy throughput: roughly two full cycles a day.
- What is an equivalent full cycle?
- Total energy discharged (or charged) divided by the battery's usable capacity. Two half-depth cycles count as one equivalent full cycle.
- How do companies account for cycle life?
- Some depreciate batteries by cycles used. Nomad Transportable Power Systems uses a units-of-production method based on about 365 cycles a year over 17 years, about 6,205 cycles, with end of life at 70.8% of starting capacity.
- How long can storage warranties run?
- Terms vary by supplier and price. Eos offers 'an extended performance warranty of up to twenty-five (25) years at an additional cost,' priced on the customer's use case. SCE's contract with Ameresco defines a 'Base Energy Throughput' among its warranty terms, with the details redacted.